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Title: Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb)

Abstract

The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi2I9 induce small polarons, resulting in trapping of excitons by the lattice. The recombination of these self-trapped excitons is responsible for the broad PL emission. Rb3Bi2I9, Rb3Sb2I9, and Cs3Bi2I9 exhibit high resistivity and photoconductivity response under laser photoexcitation, indicating that these compounds possess potential as semiconductor hard radiation detector materials.

Authors:
ORCiD logo; ORCiD logo; ; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1368321
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials; Journal Volume: 29; Journal Issue: 9
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

McCall, Kyle M., Stoumpos, Constantinos C., Kostina, Svetlana S., Kanatzidis, Mercouri G., and Wessels, Bruce W.. Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb). United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b01184.
McCall, Kyle M., Stoumpos, Constantinos C., Kostina, Svetlana S., Kanatzidis, Mercouri G., & Wessels, Bruce W.. Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb). United States. doi:10.1021/acs.chemmater.7b01184.
McCall, Kyle M., Stoumpos, Constantinos C., Kostina, Svetlana S., Kanatzidis, Mercouri G., and Wessels, Bruce W.. Wed . "Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb)". United States. doi:10.1021/acs.chemmater.7b01184.
@article{osti_1368321,
title = {Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb)},
author = {McCall, Kyle M. and Stoumpos, Constantinos C. and Kostina, Svetlana S. and Kanatzidis, Mercouri G. and Wessels, Bruce W.},
abstractNote = {The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi2I9 induce small polarons, resulting in trapping of excitons by the lattice. The recombination of these self-trapped excitons is responsible for the broad PL emission. Rb3Bi2I9, Rb3Sb2I9, and Cs3Bi2I9 exhibit high resistivity and photoconductivity response under laser photoexcitation, indicating that these compounds possess potential as semiconductor hard radiation detector materials.},
doi = {10.1021/acs.chemmater.7b01184},
journal = {Chemistry of Materials},
number = 9,
volume = 29,
place = {United States},
year = {Wed Apr 26 00:00:00 EDT 2017},
month = {Wed Apr 26 00:00:00 EDT 2017}
}